(57) Biochemical optical resolution of DL-tryptophanes in which DL-tryptophane amides are interacted with the culture products, of their treated products, of a microorganism capable of producing amidase is described. L-tryptophane amides in racemic DL-tryptophane amides are asymmetrically hydrolyzed to form optically active L-tryptophanes at a high yield and almost all D-tryptophane amides remain without being subjected to hydrolysis. The resultant D-tryptophane amides are readily hydrolyzed, after separating L-tryptophanes, to form optically active D-tryptophanes at a high yield.